Aldehyde(s) can be produced by reacting an olefin with carbon monoxide and hydrogen in the presence of a Group 8 to 10 metal compound or in the presence of a Group 8 to 10 metal compound and phosphorus compound(s). The process is known as “hydroformylation” or “oxo process” and is an important industrial process widely used in the production of aldehyde(s).
The hydroformylation generally involves catalysts based on a rhodium compound or a combination of a rhodium compound and phosphorus compound(s) for industrial use. Among phosphorus compounds conventionally used in the hydroformylation are phosphines, such as tributylphosphine, trioctylphosphine, tricyclohexylphosphine, triphenylphosphine, and tri(p-tolyl)phosphine (See, for example, Japanese Patent Laid-Open Publication No. Hei 8-10624); monophosphites, such as triphenylphosphite, tri-n-butylphosphite, and tris(2-t-butyl-4-methylphenyl)phosphite (See, for example, The Journal of Organic Chemistry, Vol. 34, No. 2 (1969): pp. 327-330; Journal of the Chemical Society, Chemical Communications (1991): pp. 1096-1097); bisphosphites, such as bis[3,3′,5,5′-tetra-t-butyl(1,1′-biphenyl)-2,2′-diyl]-1,2-ethyldiphosphite, bis[3,3′,5,5′-tetra-t-butyl(1,1′-biphenyl)-2,2′-diyl]-2,7,9,9-tetramethyl-9H-xanthine-4,5-diyldiphosphite, and bis[3,3′-di-t-butyl-5,5′-dimethoxy(1,1′-biphenyl)-2,2′-diyl]-2,7,9,9-tetramethyl-9H-xanthine-4,5-diyldiphosphite (See, for example, Organometallics Vol. 15 (1996): pp. 835-847; Helvetica Chimica Acta Vol. 84 (2001): pp. 3269-3280). Different hydroformylation processes have been developed that make use of these phosphorus compounds.